define(function (require, exports, module) {


    function onload() {
        var R = typeof Reflect === 'object' ? Reflect : null
        var ReflectApply = R && typeof R.apply === 'function'
            ? R.apply
            : function ReflectApply(target, receiver, args) {
                return Function.prototype.apply.call(target, receiver, args);
            }

        var ReflectOwnKeys
        if (R && typeof R.ownKeys === 'function') {
            ReflectOwnKeys = R.ownKeys
        } else if (Object.getOwnPropertySymbols) {
            ReflectOwnKeys = function ReflectOwnKeys(target) {
                return Object.getOwnPropertyNames(target)
                    .concat(Object.getOwnPropertySymbols(target));
            };
        } else {
            ReflectOwnKeys = function ReflectOwnKeys(target) {
                return Object.getOwnPropertyNames(target);
            };
        }

        function ProcessEmitWarning(warning) {
            if (console && console.warn) console.warn(warning);
        }

        var NumberIsNaN = Number.isNaN || function NumberIsNaN(value) {
            return value !== value;
        }

        function EventEmitter() {
            EventEmitter.init.call(this);
        }

// Backwards-compat with node 0.10.x
        EventEmitter.EventEmitter = EventEmitter;

        EventEmitter.prototype._events = undefined;
        EventEmitter.prototype._eventsCount = 0;
        EventEmitter.prototype._maxListeners = undefined;

// By default EventEmitters will print a warning if more than 10 listeners are
// added to it. This is a useful default which helps finding memory leaks.
        var defaultMaxListeners = 10;

        function checkListener(listener) {
            if (typeof listener !== 'function') {
                throw new TypeError('The "listener" argument must be of type Function. Received type ' + typeof listener);
            }
        }

        Object.defineProperty(EventEmitter, 'defaultMaxListeners', {
            enumerable: true,
            get: function() {
                return defaultMaxListeners;
            },
            set: function(arg) {
                if (typeof arg !== 'number' || arg < 0 || NumberIsNaN(arg)) {
                    throw new RangeError('The value of "defaultMaxListeners" is out of range. It must be a non-negative number. Received ' + arg + '.');
                }
                defaultMaxListeners = arg;
            }
        });

        EventEmitter.init = function() {

            if (this._events === undefined ||
                this._events === Object.getPrototypeOf(this)._events) {
                this._events = Object.create(null);
                this._eventsCount = 0;
            }

            this._maxListeners = this._maxListeners || undefined;
        };

        // Obviously not all Emitters should be limited to 10. This function allows
        // that to be increased. Set to zero for unlimited.
        EventEmitter.prototype.setMaxListeners = function setMaxListeners(n) {
            if (typeof n !== 'number' || n < 0 || NumberIsNaN(n)) {
                throw new RangeError('The value of "n" is out of range. It must be a non-negative number. Received ' + n + '.');
            }
            this._maxListeners = n;
            return this;
        };

        function _getMaxListeners(that) {
            if (that._maxListeners === undefined)
                return EventEmitter.defaultMaxListeners;
            return that._maxListeners;
        }

        EventEmitter.prototype.getMaxListeners = function getMaxListeners() {
            return _getMaxListeners(this);
        };

        EventEmitter.prototype.emit = function emit(type) {
            var args = [];
            for (var i = 1; i < arguments.length; i++) args.push(arguments[i]);
            var doError = (type === 'error');

            var events = this._events;
            if (events !== undefined)
                doError = (doError && events.error === undefined);
            else if (!doError)
                return false;

            // If there is no 'error' event listener then throw.
            if (doError) {
                var er;
                if (args.length > 0)
                    er = args[0];
                if (er instanceof Error) {
                    // Note: The comments on the `throw` lines are intentional, they show
                    // up in Node's output if this results in an unhandled exception.
                    throw er; // Unhandled 'error' event
                }
                // At least give some kind of context to the user
                var err = new Error('Unhandled error.' + (er ? ' (' + er.message + ')' : ''));
                err.context = er;
                throw err; // Unhandled 'error' event
            }

            var handler = events[type];

            if (handler === undefined)
                return false;

            if (typeof handler === 'function') {
                ReflectApply(handler, this, args);
            } else {
                var len = handler.length;
                var listeners = arrayClone(handler, len);
                for (var i = 0; i < len; ++i)
                    ReflectApply(listeners[i], this, args);
            }

            return true;
        };

        function _addListener(target, type, listener, prepend) {
            var m;
            var events;
            var existing;

            checkListener(listener);

            events = target._events;
            if (events === undefined) {
                events = target._events = Object.create(null);
                target._eventsCount = 0;
            } else {
                // To avoid recursion in the case that type === "newListener"! Before
                // adding it to the listeners, first emit "newListener".
                if (events.newListener !== undefined) {
                    target.emit('newListener', type,
                        listener.listener ? listener.listener : listener);

                    // Re-assign `events` because a newListener handler could have caused the
                    // this._events to be assigned to a new object
                    events = target._events;
                }
                existing = events[type];
            }

            if (existing === undefined) {
                // Optimize the case of one listener. Don't need the extra array object.
                existing = events[type] = listener;
                ++target._eventsCount;
            } else {
                if (typeof existing === 'function') {
                    // Adding the second element, need to change to array.
                    existing = events[type] =
                        prepend ? [listener, existing] : [existing, listener];
                    // If we've already got an array, just append.
                } else if (prepend) {
                    existing.unshift(listener);
                } else {
                    existing.push(listener);
                }

                // Check for listener leak
                m = _getMaxListeners(target);
                if (m > 0 && existing.length > m && !existing.warned) {
                    existing.warned = true;
                    // No error code for this since it is a Warning
                    // eslint-disable-next-line no-restricted-syntax
                    var w = new Error('Possible EventEmitter memory leak detected. ' +
                        existing.length + ' ' + String(type) + ' listeners ' +
                        'added. Use emitter.setMaxListeners() to ' +
                        'increase limit');
                    w.name = 'MaxListenersExceededWarning';
                    w.emitter = target;
                    w.type = type;
                    w.count = existing.length;
                    ProcessEmitWarning(w);
                }
            }

            return target;
        }

        EventEmitter.prototype.addListener = function addListener(type, listener) {
            return _addListener(this, type, listener, false);
        };

        EventEmitter.prototype.on = EventEmitter.prototype.addListener;

        EventEmitter.prototype.prependListener =
            function prependListener(type, listener) {
                return _addListener(this, type, listener, true);
            };

        function onceWrapper() {
            if (!this.fired) {
                this.target.removeListener(this.type, this.wrapFn);
                this.fired = true;
                if (arguments.length === 0)
                    return this.listener.call(this.target);
                return this.listener.apply(this.target, arguments);
            }
        }

        function _onceWrap(target, type, listener) {
            var state = { fired: false, wrapFn: undefined, target: target, type: type, listener: listener };
            var wrapped = onceWrapper.bind(state);
            wrapped.listener = listener;
            state.wrapFn = wrapped;
            return wrapped;
        }

        EventEmitter.prototype.once = function once(type, listener) {
            checkListener(listener);
            this.on(type, _onceWrap(this, type, listener));
            return this;
        };

        EventEmitter.prototype.prependOnceListener =
            function prependOnceListener(type, listener) {
                checkListener(listener);
                this.prependListener(type, _onceWrap(this, type, listener));
                return this;
            };

        // Emits a 'removeListener' event if and only if the listener was removed.
        EventEmitter.prototype.removeListener =
            function removeListener(type, listener) {
                var list, events, position, i, originalListener;

                checkListener(listener);

                events = this._events;
                if (events === undefined)
                    return this;

                list = events[type];
                if (list === undefined)
                    return this;

                if (list === listener || list.listener === listener) {
                    if (--this._eventsCount === 0)
                        this._events = Object.create(null);
                    else {
                        delete events[type];
                        if (events.removeListener)
                            this.emit('removeListener', type, list.listener || listener);
                    }
                } else if (typeof list !== 'function') {
                    position = -1;

                    for (i = list.length - 1; i >= 0; i--) {
                        if (list[i] === listener || list[i].listener === listener) {
                            originalListener = list[i].listener;
                            position = i;
                            break;
                        }
                    }

                    if (position < 0)
                        return this;

                    if (position === 0)
                        list.shift();
                    else {
                        spliceOne(list, position);
                    }

                    if (list.length === 1)
                        events[type] = list[0];

                    if (events.removeListener !== undefined)
                        this.emit('removeListener', type, originalListener || listener);
                }

                return this;
            };

        EventEmitter.prototype.off = EventEmitter.prototype.removeListener;

        EventEmitter.prototype.removeAllListeners =
            function removeAllListeners(type) {
                var listeners, events, i;

                events = this._events;
                if (events === undefined)
                    return this;

                // not listening for removeListener, no need to emit
                if (events.removeListener === undefined) {
                    if (arguments.length === 0) {
                        this._events = Object.create(null);
                        this._eventsCount = 0;
                    } else if (events[type] !== undefined) {
                        if (--this._eventsCount === 0)
                            this._events = Object.create(null);
                        else
                            delete events[type];
                    }
                    return this;
                }

                // emit removeListener for all listeners on all events
                if (arguments.length === 0) {
                    var keys = Object.keys(events);
                    var key;
                    for (i = 0; i < keys.length; ++i) {
                        key = keys[i];
                        if (key === 'removeListener') continue;
                        this.removeAllListeners(key);
                    }
                    this.removeAllListeners('removeListener');
                    this._events = Object.create(null);
                    this._eventsCount = 0;
                    return this;
                }

                listeners = events[type];

                if (typeof listeners === 'function') {
                    this.removeListener(type, listeners);
                } else if (listeners !== undefined) {
                    // LIFO order
                    for (i = listeners.length - 1; i >= 0; i--) {
                        this.removeListener(type, listeners[i]);
                    }
                }

                return this;
            };

        function _listeners(target, type, unwrap) {
            var events = target._events;

            if (events === undefined)
                return [];

            var evlistener = events[type];
            if (evlistener === undefined)
                return [];

            if (typeof evlistener === 'function')
                return unwrap ? [evlistener.listener || evlistener] : [evlistener];

            return unwrap ?
                unwrapListeners(evlistener) : arrayClone(evlistener, evlistener.length);
        }

        EventEmitter.prototype.listeners = function listeners(type) {
            return _listeners(this, type, true);
        };

        EventEmitter.prototype.rawListeners = function rawListeners(type) {
            return _listeners(this, type, false);
        };

        EventEmitter.listenerCount = function(emitter, type) {
            if (typeof emitter.listenerCount === 'function') {
                return emitter.listenerCount(type);
            } else {
                return listenerCount.call(emitter, type);
            }
        };

        EventEmitter.prototype.listenerCount = listenerCount;
        function listenerCount(type) {
            var events = this._events;

            if (events !== undefined) {
                var evlistener = events[type];

                if (typeof evlistener === 'function') {
                    return 1;
                } else if (evlistener !== undefined) {
                    return evlistener.length;
                }
            }

            return 0;
        }

        EventEmitter.prototype.eventNames = function eventNames() {
            return this._eventsCount > 0 ? ReflectOwnKeys(this._events) : [];
        };

        function arrayClone(arr, n) {
            var copy = new Array(n);
            for (var i = 0; i < n; ++i)
                copy[i] = arr[i];
            return copy;
        }

        function spliceOne(list, index) {
            for (; index + 1 < list.length; index++)
                list[index] = list[index + 1];
            list.pop();
        }

        function unwrapListeners(arr) {
            var ret = new Array(arr.length);
            for (var i = 0; i < ret.length; ++i) {
                ret[i] = arr[i].listener || arr[i];
            }
            return ret;
        }

        function once(emitter, name) {
            return new Promise(function (resolve, reject) {
                function errorListener(err) {
                    emitter.removeListener(name, resolver);
                    reject(err);
                }

                function resolver() {
                    if (typeof emitter.removeListener === 'function') {
                        emitter.removeListener('error', errorListener);
                    }
                    resolve([].slice.call(arguments));
                };

                eventTargetAgnosticAddListener(emitter, name, resolver, { once: true });
                if (name !== 'error') {
                    addErrorHandlerIfEventEmitter(emitter, errorListener, { once: true });
                }
            });
        }

        function addErrorHandlerIfEventEmitter(emitter, handler, flags) {
            if (typeof emitter.on === 'function') {
                eventTargetAgnosticAddListener(emitter, 'error', handler, flags);
            }
        }

        function eventTargetAgnosticAddListener(emitter, name, listener, flags) {
            if (typeof emitter.on === 'function') {
                if (flags.once) {
                    emitter.once(name, listener);
                } else {
                    emitter.on(name, listener);
                }
            } else if (typeof emitter.addEventListener === 'function') {
                // EventTarget does not have `error` event semantics like Node
                // EventEmitters, we do not listen for `error` events here.
                emitter.addEventListener(name, function wrapListener(arg) {
                    // IE does not have builtin `{ once: true }` support so we
                    // have to do it manually.
                    if (flags.once) {
                        emitter.removeEventListener(name, wrapListener);
                    }
                    listener(arg);
                });
            } else {
                throw new TypeError('The "emitter" argument must be of type EventEmitter. Received type ' + typeof emitter);
            }
        }

        const result = EventEmitter;
        result.once = once;

        return result
    }

    module.exports = {
        onload
    }
});
